Surface features by azimuthal angle

ABSTRACT

Provided herein is an apparatus, including a photon emitter configured to emit photons onto a surface of an article at a number of azimuthal angles; and a processing element configured to process photon-detector-array signals corresponding to photons scattered from surface features of the article and generate one or more surface features maps for the article from the photon-detector-array signals corresponding to the photons scattered from the surface features of the article.

CROSS REFERENCE

This application is a continuation application and claims the benefitand priority to the U.S. patent application Ser. No. 14/096,001, filedon Dec. 3, 2013 which claims the benefit and priority to the U.S.Provisional Patent Application No. 61/829,157, filed May 30, 2013, allof which are incorporated herein by reference.

BACKGROUND

An article fabricated on a production line may be inspected for certainfeatures, including defects that might degrade the performance of thearticle or a system including the article. For example, a hard disk fora hard disk drive may be fabricated on a production line and inspectedfor certain surface features, including surface and subsurface defectsthat might degrade the performance of the disk or the hard disk drive.Accordingly, apparatuses and methods may be used to inspect articles forfeatures such as defects.

SUMMARY

Provided herein is an apparatus, including a photon emitting meansconfigured to emit photons onto a surface of an article at a number ofazimuthal angles; and a processing means configured to processphoton-detector-array signals corresponding to photons scattered fromsurface features of the article and generate one or more surfacefeatures maps for the article from the photon-detector-array signalscorresponding to the photons scattered from the surface features of thearticle.

These and other features and aspects of the concepts provided herein maybe better understood with reference to the following drawings,description, and appended claims.

DRAWINGS

FIG. 1A-1B provide a schematic illustrating detection of surfacefeatures of articles according to one aspect of the present embodiments.

FIG. 2 provides a schematic illustrating photon scattering from asurface feature of an article according to one aspect of the presentembodiments.

FIG. 3 provides a schematic illustrating photons scattering from asurface feature of an article, through an optical component, and onto aphoton detector array according to one aspect of the presentembodiments.

FIG. 4 provides an image of a surface features map of an articleaccording to one aspect of the present embodiments.

FIG. 5 provides a close-up image of a surface features map of an articleaccording to one aspect of the present embodiments.

FIG. 6A (top) provides a close-up image of a surface feature from asurface features map, and FIG. 6A (bottom) provides a photon scatteringintensity distribution of the surface feature, according to aspects ofthe present embodiments.

FIG. 6B (top) provides a close-up, pixel-interpolated image of a surfacefeature from a surface features map, and FIG. 6B (bottom) provides aphoton scattering intensity distribution of the pixel-interpolatedsurface feature, according to aspects of the present embodiments.

FIG. 7A provides a schematic illustrating detection of surface featuresof articles at a first azimuthal angle according to one aspect of thepresent embodiments.

FIG. 7B provides a schematic illustrating detection of surface featuresof articles at a second azimuthal angle according to one aspect of thepresent embodiments.

FIG. 7C provides a schematic illustrating detection of surface featuresof articles at a first azimuthal angle according to one aspect of thepresent embodiments.

FIG. 7D provides a schematic illustrating detection of surface featuresof articles at a second azimuthal angle according to one aspect of thepresent embodiments.

FIG. 8A provides an image of a surface features map of an article at afirst azimuthal angle according to one aspect of the presentembodiments.

FIG. 8B provides an image of a surface features map of an article at asecond azimuthal angle according to one aspect of the presentembodiments.

DESCRIPTION

Before some particular embodiments are described and/or illustrated ingreater detail, it should be understood by persons having ordinary skillin the art that the particular embodiments provided herein do not limitthe concepts provided herein, as elements in such particular embodimentsmay vary. It should likewise be understood that a particular embodimentprovided herein has elements which may be readily separated from theparticular embodiment and optionally combined with or substituted forelements in any of several other embodiments described and/orillustrated herein.

It should also be understood by persons having ordinary skill in the artthat the terminology used herein is for the purpose of describing someparticular embodiments, and the terminology does not limit the conceptsprovided herein. Unless indicated otherwise, ordinal numbers (e.g.,first, second, third, etc.) are used to distinguish or identifydifferent elements or steps in a group of elements or steps, and do notsupply a serial or numerical limitation. For example, “first,” “second,”and “third” elements or steps need not necessarily appear in that order,and embodiments need not necessarily be limited to the three elements orsteps. It should also be understood that, unless indicated otherwise,any labels such as “left,” “right,” “front,” “back,” “top,” “bottom,”“forward,” “reverse,” “clockwise,” “counter clockwise,” “up,” “down,” orother similar terms such as “upper,” “lower,” “aft,” “fore,” “vertical,”“horizontal,” “proximal,” “distal,” and the like are used forconvenience and are not intended to imply, for example, any particularfixed location, orientation, or direction. Instead, such labels are usedto reflect, for example, relative location, orientation, or directions.It should also be understood that the singular forms of “a,” “an,” and“the” include plural references unless the context clearly dictatesotherwise.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by persons of ordinaryskill in the art.

An article fabricated on a production line may be inspected for certainfeatures, including defects that might degrade the performance of thearticle or a system including the article. For example, a hard disk fora hard disk drive may be fabricated on a production line and inspectedfor certain surface features, including surface and subsurface defectsthat might degrade the performance of the disk or the hard disk drive.Provided herein are apparatuses and methods for inspecting articles todetect, map, and/or characterize certain surface features such assurface and/or subsurface defects.

With respect to articles that may be inspected with apparatuses andmethods herein, such articles include any article of manufacture or aworkpiece thereof in any stage of manufacture having one or moresurfaces (e.g., one or more optically smooth surfaces), examples ofwhich include, but are not limited to, semiconductor wafers, magneticrecording media (e.g., hard disks for hard disk drives), and workpiecesthereof in any stage of manufacture, including transparent articles suchas glass blanks for magnetic recording media. Such articles may beinspected for certain surface features, including surface and/orsubsurface defects that might degrade the performance of the article,which surface and/or subsurface defects include particle and staincontamination, as well as defects including scratches and voids. Withrespect to particle contamination, for example, particles trapped on asurface of an intermediate hard disk (i.e., workpiece) for a hard diskdrive may damage subsequently sputtered films. Particle contaminationmay also contaminate a finished surface of a hard disk drive, leading toscratch formation, debris generation, and corruption of the spacingbetween the hard disk and the read-write head. As such, it is importantto inspect articles with apparatus and methods herein to correctmanufacturing trends leading to surface and/or subsurface defects and toincrease product quality.

FIG. 1A provides a basis from which to begin a description of featuresof the apparatuses and methods provided herein. In view of theforegoing, FIG. 1A provides a non-limiting schematic for detecting,mapping, and/or characterizing surface features of articles illustratingan apparatus 100 including a photon emitter 110, an optical setup 120including an optical component, a photon detector array 130, a computeror equivalent device 140, an optional stage 150 configured to support anarticle 160 and/or rotate an article 160 through a number of azimuthalangles, and a surface features map 170 of a surface of the article 160.As such, FIG. 1A provides a basis from which to begin a description ofphoton emitters, optical components of the optical setup, photondetector arrays, etc. The apparatuses and methods provided herein arenot limited to FIG. 1A, as additional embodiments are provided herein,and additional embodiments may be realized by the features provided inmore detail herein.

An apparatus may include a single photon emitter (e.g., see photonemitter 110 of FIG. 1A) or a number of photon emitters (e.g., see photonemitters 110A-C of FIGS. 7C and 7D). In some embodiments, for example,the apparatus may include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10photon emitter(s). In some embodiments, for example, the apparatus mayinclude no more than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 photon emitter(s).Combinations of the foregoing may also be used to describe the number ofphoton emitters of the apparatus. In some embodiments, for example, theapparatus may include at least 2 photon emitters and no more than 10photon emitters (e.g., between 2 and 10 photon emitters), such as atleast 2 photon emitters and no more than 6 photon emitters (e.g.,between 2 and 6 photon emitters), including at least 2 photon emittersand no more than 4 photon emitters (e.g., between 2 and 4 photonemitters). A single photon emitter may be used to emit photons onto asurface of an article, such as the entire surface of the article or somepredetermined portion of the surface of the article (e.g., forgradational rotation of the article for piecewise inspection, ifdesired); each photon emitter of a number of photon emitters may be usedto emit photons onto the surface of the article, such as the entiresurface of the article or some predetermined portion of the surface ofthe article, at different times and/or at the same time in anycollection of photon emitters (e.g., see photon emitters 110A-C of FIGS.7C and 7D). Further with respect to the number of photon emitters, eachphoton emitter of a number of photon emitters may be the same ordifferent, or some combination thereof (e.g., at least 2 of the samephoton emitter, with the remainder of photon emitters being different;at least 4 of the same photon emitter, with the remainder of photonemitters being different; etc.). In some embodiments, for example, theapparatus may include at least two different photon emitters, whereinthe two different photon emitters are each separately configured to emitphotons onto a surface of an article, such as the entire surface of thearticle or some predetermined portion of the surface of the article.

Whether the apparatus includes a single photon emitter or a number ofphoton emitters, each photon emitter may emit photons onto a surface ofan article at one or more distances and/or angles optimized for one ormore types of features, which types of features are described in moredetail herein. One angle may be equal to the glancing angle, which isthe complement of the angle of incidence, and which angle of incidenceis the angle between a ray including the emitted photons incident on thesurface of the article and the normal (e.g., a line or vectorperpendicular to the surface of the article) at the point at which theray is incident. The glancing angle may also be described as analtitudinal angle or the smallest angle between a ray including theemitted photons incident on the surface of the article and the surfaceat the point at which the ray is incident. Another angle optimized forone or more types of features may be equal to the azimuthal angle, whichis described in more detail herein.

FIG. 2 provides a number of rays including emitted photons incident on asurface 162 of an article 160 that form a glancing angle with thesurface 162. FIG. 2 further provides a number of rays includingreflected photons that form an angle of reflection with the normal tothe surface, which angle of reflection is equal in magnitude to theangle of incidence. FIG. 2 even further provides a number of raysincluding scattered photons from a feature 164 on the surface 162 of thearticle 160, which rays including scattered photons form various scatterangles. A photon emitter may emit photons at a glancing angle rangingfrom 0° to 90°, wherein a glancing angle of 0° represents the photonemitter emitting photons onto the surface of the article from a side ofthe article, and wherein a glancing angle of 90° represents the photonemitter emitting photons onto the surface of the article from directlyabove the article. In some embodiments, for example, a photon emittermay emit photons onto a surface of an article such that the glancingangle is at least 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°,55°, 60°, 65°, 70°, 75°, 80°, 85°, or 90°. In some embodiments, forexample, a photon emitter may emit photons onto a surface of an articlesuch that the glancing angle is no more than 90°, 85°, 80°, 75°, 70°,65°, 60°, 55°, 50°, 45°, 40°, 35°, 30°, 25°, 20°, 15°, 10°, 5°, or 0°.Combinations of the foregoing may also be used to describe the glancingangle at which a photon emitter may emit photons onto a surface of anarticle. In some embodiments, for example, a photon emitter may emitphotons onto a surface of an article such that the glancing angle is atleast a 0° and no more than 90° (i.e., between 0° and 90°), such as atleast 0° and no more than 45° (i.e., between 0° and 45°), including atleast 45° and no more than 90° (i.e., between 45° and 90°).

A photon emitter may emit photons onto a surface of an article, such asthe entire surface or some predetermined portion of the surface (e.g.,for gradational rotation of the article for piecewise inspection, ifdesired). The photon emitter may further emit photons onto the entiresurface of the article or some predetermined portion of the surface suchthat the entire surface or the predetermined portion of the surface isuniformly or homogenously illuminated. Uniformly illuminating the entiresurface of the article or some predetermined portion of the surfaceincludes, but is not limited to, subjecting the entire surface of thearticle or some predetermined portion of the surface of the article tothe same or about the same quantity of photons per unit time (e.g.,photon flux), the same or about the same photon energy per unit time(e.g., photon power), and/or the same or about the same photon power perunit area (e.g., photon power density or photon flux density). Inradiometric terms, uniformly illuminating includes, but is not limitedto, subjecting the entire surface of the article or some predeterminedportion of the surface of the article to the same or about the samequantity of light per unit time, the same or about the same radiantenergy per unit time (e.g., radiant power or radiant flux), and/or thesame or about the same radiant power per unit area (e.g., irradiance orradiant flux density).

With the appreciation that photons are the elementary particles ofelectromagnetic radiation or light, a photon emitter or light source mayprovide light including a relatively wide range of wavelengths (e.g.,whole spectrum, broad spectrum, ultraviolet-visible, visible, infrared,etc.), a relatively narrow range of wavelengths (e.g., a subdivision ofultraviolet such as UVA, UVB, UVC, etc.; a subdivision of visible suchas red, green, blue, etc.; a subdivision of infrared such as nearinfrared, mid-infrared; etc.), or a particular wavelength (e.g.,monochromatic); light including a relatively wide range of frequencies(e.g., whole spectrum, broad spectrum, ultraviolet-visible, visible,infrared, etc.), a relatively narrow range of frequencies (e.g., asubdivision of ultraviolet such as UVA, UVB, UVC, etc.; a subdivision ofvisible such as red, green, blue, etc.; a subdivision of infrared suchas near infrared, mid-infrared; etc.), or a particular frequency (e.g.,monochromatic); polarized (e.g., linear polarization, circularpolarization, etc.) light, partially polarized light, or nonpolarizedlight; and/or light with different degrees of temporal and/or spatialcoherence ranging from coherent light (e.g., laser) to noncoherentlight. A photon emitter or light source may be used in conjunction withone or more optical components of an optical setup to provide lighthaving any of the foregoing qualities. Wavelength filters, for example,may be used in conjunction with a photon emitter or light source toprovide light including a relatively wide range of wavelengths orfrequencies, a relatively narrow range of wavelengths or frequencies, ora particular wavelength or frequency. Polarization filters, for example,may also be used in conjunction with a photon emitter or light source toprovide light of a desired polarization including polarized light,partially polarized light, or nonpolarized light.

In view of the foregoing, a photon emitter or light source may include alamp such as a flash lamp, including a high-speed flash lamp, configuredto minimize vibration while detecting photons scattered from surfacefeatures of an article with a photon detector array. In someembodiments, for example, a photon emitter or light source may include ahigh-speed Xe flash lamp such as a 500 W Xe flash lamp to minimizevibration while detecting photons scattered from surface features of anarticle with a photon detector array.

Also in view of the foregoing, a photon emitter or light source mayinclude a collimated light source such as a laser, including acombination of lasers, configured to emit photons onto a surface of anarticle at one or more angles. In some embodiments, for example, acombination of lasers may be provided to a laser beam shaper such thatthe combination of lasers emits photons onto a surface of an article atone angle. In some embodiments, for example, a combination of lasers maybe provided to a laser beam shaper such that the combination of lasersemits photons onto a surface of an article at multiple angles. In someembodiments, for example, at least 2, 4, 6, 8, 10, 12, 14, 16, 18, 20,22, 24, 26, 28, or 30 lasers, or even more than 30 lasers, may beprovided to a laser beam shaper such that the combination of lasersemits photons onto a surface of an article at one or more angles. Insome embodiments, for example, no more than 30, 28, 26, 24, 22, 20, 18,16, 14, 12, 10, 8, 6, 4, or 2 lasers may be provided to a laser beamshaper such that the combination of lasers emits photons onto a surfaceof an article at one or more angles. Combinations of the foregoing mayalso be used to describe combinations of lasers provided to a laser beamshaper. In some embodiments, for example, at least 2 lasers and no morethan 30 lasers (e.g., between 2 and 30 lasers), such as at least 10lasers and no more than 30 lasers (e.g., between 10 and 30 lasers),including at least 20 lasers and no more than 30 lasers (e.g., between20 and 30 lasers), and further including at least 24 lasers and no morethan 28 lasers (e.g., between 24 and 28 lasers) may be provided to alaser beam shaper such that the combination of lasers emits photons ontoa surface of an article of an article at one or more angles.

Further in view of the foregoing, a photon emitter or light source mayinclude a two-dimensional light source such as a combination of pointlight sources, including a linear combination or array, an arcuatecombination or array, etc. of point light sources configured to emitphotons onto a surface of an article. In some embodiments, for example,a two-dimensional light source may include a combination of at least 10,20, 40, 60, 80, 100, 110, 120, 140, 160, 180, or 200 point lightsources, or even more than 200 point sources. In some embodiments, forexample, a two-dimensional light source may include a combination of nomore than 200, 180, 160, 140, 120, 100, 80, 60, 40, 20, or 10 pointlight sources. Combinations of the foregoing may also be used todescribe two-dimensional light sources including combinations of pointlight sources. In some embodiments, for example, a two-dimensional lightsource may include a combination of at least 10 and no more than 200(e.g., between 10 and 200) point light sources, such as at least 40 andno more than 160 (e.g., between 40 and 160) point light sources,including at least 60 and no more than 140 (e.g., between 60 and 140)point light sources, and further including at least 80 and no more than120 (e.g., between 80 and 120) point light sources. Such point lightsources may be combined in rows and columns of a two-dimensional array,including linearly combined to form a two-dimensional light source suchas a strip light. Such point light sources may be arcuately combined toform a two-dimensional light source such as a ring light. In someembodiments, for example, a photon emitter or light source may include atwo-dimensional light source including at least 60 point light sources,such as a ring light including at least 60 point light sources,including a ring light including at least 60 light-emitting diodes(“LEDs”), and further including a ring light including at least 100LEDs. A two-dimensional light source including LEDs may include whiteLEDs, wherein each LED has a power of at least 10 mW. An LED-based ringlight may enhance features such as scratches (e.g., circumferentialscratches) and/or voids in surfaces of articles, especially when theLED-based ring light is configured to emit photons onto the surfaces ofthe articles with lower angles (e.g., glancing angle equal to or lessthan 45°).

The apparatus may further include an optical setup (e.g., optical setupincluding one or more of optical components 120 of FIG. 1A), whichoptical setup may manipulate photons emitted from one or more photonemitters, photons reflected from a surface of an article, and/or photonsscattered from surface features of an article. With the appreciationthat photons are the elementary particles of electromagnetic radiationor light, the optical setup may manipulate light emitted from one ormore photon emitters, light reflected from a surface of an article,and/or light scattered from surface features of an article. The opticalsetup up may include any of a number of optical components positionedbefore the article such that the optical components may be used tomanipulate photons emitted from one or more photon emitters beforeuniformly or homogenously illuminating the entire surface or thepredetermined portion of the surface of the article. Alternatively, orin addition, the optical setup up may include any of a number of opticalcomponents positioned after the article such that the optical componentsmay be used to manipulate photons reflected from the surface of thearticle or scattered from surface features of the article.Alternatively, or in addition, an optical component including thearticle (e.g., article 160 of FIG. 1A) may be used to manipulate (e.g.,reflect) photons. The forgoing optical components may include, but arenot limited to, optical components such as lenses, filters, gratings,and mirrors, which mirrors include articles having optically smoothsurfaces.

With respect to optical components such as lenses, the optical setup mayinclude a single lens or a number of lenses, including, but not limitedto, a combination of a lens coupled to a photon detector array (e.g., alens-and-photon-detector-array combination including lens 120 and photondetector array 130 of FIG. 1A) configured for collecting and detectingphotons scattered from surface features of articles. The lens coupled tothe photon detector array may have an entrance pupil and an exit pupil,and additional optical components such as lenses (e.g., lenses inaddition to the lens coupled to the photon detector array), filters,gratings, and mirrors, may be positioned in any combination of one ormore optical components at or near the entrance pupil of the lenscoupled to the photon detector array, at or near the exit pupil of thelens coupled to the photon detector array (i.e., in-between the exitpupil of the lens and the photon detector array), or some combinationthereof to manipulate photons scattered from surface features ofarticles. The lens coupled to the photon detector array may be anobjective lens, such as a telecentric lens, including an object-spacetelecentric lens (i.e., entrance pupil at infinity), an image-spacetelecentric lens (i.e., exit pupil at infinity), or a double telecentriclens (i.e., both pupils at infinity). Coupling a telecentric lens to aphoton detector array reduces errors with respect to the position ofsurface features of articles, reduces distortion of surface features ofarticles, enables quantitative analysis of photons scattered fromsurface features of articles, which quantitative analysis includesintegration of photon scattering intensity distribution for sizedetermination of surface features of articles.

With respect to optical components such as filters, the optical setupmay include a filter or a number of filters including, but not limitedto, one or more wavelength filters, band-pass filters, polarizationfilters, coherence filters, periodic array-tuned filters, and phasefilters. As described herein, when one or more of such filters ispositioned before an article to manipulate photons emitted from a photonemitter, photons/light having any of a number of different qualities maybe provided to a surface of the article. When one or more of suchfilters is positioned after an article to manipulate photons scatteredfrom surface features of the article, the one or more filters may beused for distinguishing between surface features of the article. Forexample, a wavelength filter may be used to distinguish between surfacefeatures known to differentially scatter photons with respect towavelength; a polarization filter may be used to distinguish betweensurface features known to differentially scatter photons with respect topolarization; a coherence filter may be used to distinguish betweensurface features known to differentially scatter photons with respect tocoherence; and a phase filter or waveplate may be used to distinguishbetween surface features known to differentially scatter photons withrespect to phase. In some embodiments, for example, an optical componentsuch as a filter may be positioned at or near the entrance pupil of alens (e.g., telecentric lens) coupled to a photon detector array. Insome embodiments, for example, an optical component such as a filter maybe positioned at or near the exit pupil of a lens (e.g., telecentriclens) coupled to a photon detector array.

With respect to optical components including reflective surfaces such asmirrors, the optical setup may include one or more mirrors of anycurvature including, but not limited to, one or more mirrors selectedfrom optical-grade mirrors and one-way mirrors, including articlesincluding optically smooth surfaces. The one or more mirrors may bepositioned about an apparatus to manipulate photons emitted from one ormore photon emitters, reflected from a surface of an article, scatteredfrom surface features of an article, or combinations thereof. As such,the one or more mirrors may be positioned in a light path before anarticle (e.g., a one-way mirror between a photon emitter and thearticle); in the light path after an article; in the light path under anarticle, for example, parallelly proximate to a transparent article; orin combinations thereof. In some embodiments, for example, one or moremirrors may be used to redirect photons reflected off a surface of anarticle back onto the surface of the article, thereby recycling photonsthat would otherwise be lost to the environment.

To detect photons scattered from surface features of articles, anapparatus may further include a single photon detector array (e.g., seephoton detector array 130 of FIG. 1A) including a number of photondetectors or a number of photon detector arrays, each including a numberof photon detectors. In some embodiments, for example, the number ofphoton detector arrays may include at least 2, 3, 4, 5, 6, 7, 8, 9, or10 photon detector arrays (For example, FIG. 1B shows two photondetectors 130A and 130B with two optical components 120A and 120B). Insome embodiments, for example, the number of photon detector arrays mayinclude no more than 10, 9, 8, 7, 6, 5, 4, 3, or 2 photon detectorarrays. Combinations of the foregoing may also be used to describe thenumber of photon detector arrays. In some embodiments, for example, thenumber of photon detector arrays may include at least 2 photon detectorarrays and no more than 10 photon detector arrays (e.g., between 2 and10 photon detector arrays), such as at least 2 photon detector arraysand no more than 5 photon detector arrays (e.g., between 2 and 5 photondetector arrays). Further with respect to the number of photon detectorarrays, each photon detector array of the number of photon detectorarrays may be the same or different, or some combination thereof (e.g.,at least 2 of the same photon detector array, with the remainder ofphoton detector arrays being different; at least 3 of the same photondetector array, with the remainder of photon detector arrays beingdifferent; etc.).

Whether the apparatus includes a single photon detector array or anumber of photon detector arrays, each photon detector array may beoriented to detect photons scattered from surface features of an articleat one or more distances and/or angles for an optimum acceptance ofphotons (e.g., maximum acceptance of photons with minimum backgroundnoise) scattered from one or more types of features, which types offeatures are described in more detail herein. Likewise, alens-and-photon-detector-array combination may be oriented to collectand detect photons scattered from surface features of an article at oneor more distances and/or angles for an optimum acceptance of photonsscattered from one or more types of features. One angle may be the anglebetween a ray including the center line axis of the lens and/or thephoton detector array extended to the surface of the article and thenormal (e.g., a line or vector perpendicular to the surface of thearticle) at the point at which the ray is extended. The angle,optionally in combination with an aperture that may be optimally sizedfor maximum acceptance of scattered photons with minimum backgroundnoise, or optionally in combination with an aperture that may bevariably sized, such as more widely sized or more narrowly sized torespectively accept a wider range or narrower range of scatteredphotons, may be oriented to allow for acceptance of scattered photonshaving a number of scatter angles, which scattered photons may bescattered from one or more types of features. A scatter angle may bedifferent than the angle of reflection, which angle of reflection isequal in magnitude to the angle of incidence as described herein. FIG. 2provides a number of rays including photons scattered from a feature 164on a surface 162 of an article 160, which rays represent various scatterangles.

In view of the foregoing, the angle at which a photon detector array orlens-and-photon-detector-array combination may be oriented ranges from0° to 90°, inclusive, wherein an angle of 0° represents orientation ofthe photon detector array or the lens-and-photon-detector-arraycombination directly above the article, and wherein an angle of 90°represents orientation of the photon detector array orlens-and-photon-detector-array combination at a side of an article. Insome embodiments, for example, a photon detector array orlens-and-photon-detector-array combination may be oriented at an angleof at least 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°,60°, 65°, 70°, 75°, 80°, 85°, or 90°. In some embodiments, for example,a photon detector array or lens-and-photon-detector-array combinationmay be oriented at an angle of no more than 90°, 85°, 80°, 75°, 70°,65°, 60°, 55°, 50°, 45°, 40°, 35°, 30°, 25°, 20°, 15°, 10°, or 5°, or0°. Combinations of the foregoing may also be used to describe the angleat which the photon detector array or lens-and-photon-detector-arraycombination may be oriented. In some embodiments, for example, a photondetector array or lens-and-photon-detector-array combination may beoriented at an angle of at least a 0° and no more than a 90° (i.e.,between 0° and 90°), such as least 0° and no more than 45° (i.e.,between 0° and 45°) or at least 45° and no more than 90° (i.e., between45° and 90°).

The photon detector array, optionally in combination with a lens (e.g.,telecentric lens), may detect photons scattered from surface features ofan article, such as the entire surface of the article or somepredetermined portion of the surface of the article. The photon detectorarray, optionally in combination with a lens (e.g., telecentric lens),may detect photons scattered from surface features of an article, suchas the entire surface of the article or some predetermined portion ofthe surface of the article, while oriented at a distance and/or an anglefor an optimum acceptance of photons (e.g., maximum acceptance ofphotons with minimum background noise) scattered from one or more typesof features. As provided herein, the angle for an optimum acceptance ofphotons scattered from one or more types of features may allow foracceptance of scattered photons respectively having a number of scatterangles, which scattered photons may respectively be scattered from oneor more types of features.

With the appreciation that photons are the elementary particles ofelectromagnetic radiation or light, a photon detector array or lightdetector array may detect light including a relatively wide range ofwavelengths (e.g., whole spectrum, broad spectrum, ultraviolet-visible,visible, infrared, etc.), a relatively narrow range of wavelengths(e.g., a subdivision of ultraviolet such as UVA, UVB, UVC, etc.; asubdivision of visible such as red, green, blue, etc.; a subdivision ofinfrared such as near infrared, mid-infrared; etc.), or a particularwavelength (e.g., monochromatic); light including a relatively widerange of frequencies (e.g., whole spectrum, broad spectrum,ultraviolet-visible, visible, infrared, etc.), a relatively narrow rangeof frequencies (e.g., a subdivision of ultraviolet such as UVA, UVB,UVC, etc.; a subdivision of visible such as red, green, blue, etc.; asubdivision of infrared such as near infrared, mid-infrared; etc.), or aparticular frequency (e.g., monochromatic); polarized (e.g., linearpolarization, circular polarization, etc.) light, partially polarizedlight, or nonpolarized light; and/or light with different degrees oftemporal and/or spatial coherence ranging from coherent light (e.g.,laser) to noncoherent light. As discussed herein, a photon detectorarray or light detector array may be used in conjunction with one ormore optical components of an optical setup to detect light having anyof the foregoing qualities.

The photon detector array may include a number of pixel sensors, whichpixel sensors, in turn, may each include a photon detector (e.g., aphotodiode) coupled to a circuit including a transistor configured foramplification. Features of a photon detector array including such pixelsensors include, but are not limited to, low temperature operation(e.g., down to −40° C.), low electron noise (e.g., 2-10 e-RMS; 1 e-RMS;<1 e-RMS; etc.), wide dynamic range (e.g., 30,000:1, 8,500:1; 3,000:1;etc.), and/or decreased photon/light collection time. A photon detectorarray may include a large number of pixel sensors (e.g., ≥1,000,000 or≥1M pixel sensors) arranged in rows and columns of a two-dimensionalarray, wherein each pixel sensor includes a photon detector coupled toan amplifier. In some embodiments, for example, a photon detector arraymay include at least 1M, 2M, 3M, 4M, 5M, 6M, 7M, 8M, 9M, 10M, or more,pixel sensors arranged in rows and columns of a two-dimensional array.In some embodiments, for example, a photon detector array may include nomore than 10M, 9M, 8M, 7M, 6M, 5M, 4M, 3M, 2M, or 1M, pixel sensorsarranged in rows and columns of a two-dimensional array. Combinations ofthe foregoing may also be used to describe the number of pixel sensorsin a photon detector array. In some embodiments, for example, a photondetector array may include at least 1M and no more than 10M (e.g.,between 1M and 10M) pixel sensors arranged in rows and columns of atwo-dimensional array, such as at least 1M and no more than 8M (e.g.,between 1M and 8M) pixel sensors, including at least 1M and no more than6M (e.g., between 1M and 6M) pixel sensors, further including at least2M and no more than 6M (e.g., between 1M and 6M) pixel sensors, and evenfurther including at least 2M and no more than 5M (e.g., between 2M and5M) pixel sensors.

Due to surface reflections of surface features of articles and/or smallangle scattering (e.g., 4π scattering), surface features may appear muchlarger in size enabling pixel sensors larger the than surface featuresto be used. In some embodiments, for example, a photon detector arraymay include micrometer-sized (i.e., admits of μm units as measured)pixel sensors at least 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9μm, or 10 μm in their smallest dimension. In some embodiments, forexample, a photon detector array may include micrometer-sized pixelsensors no more than 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2μm, or 1 μm in their smallest dimension. Combinations of the foregoingmay also be used to describe dimensions of micrometer-sized pixelsensors in photon detector arrays. In some embodiments, for example, aphoton detector array may include micrometer-sized pixel sensors atleast 1 μm and no more than 10 μm (e.g., between 1 μm and 10 μm) intheir smallest dimension, such as at least 1 μm and no more than 7 μm(e.g., between 1 μm and 7 μm), including at least 4 μm and no more than10 μm (e.g., between 4 μm and 10 μm), and further including at least 4μm and no more than 7 μm (e.g., between 4 μm and 7 μm). Suchmicrometer-sized pixel sensors may be used in the apparatus fordetecting, mapping, and/or characterizing surface features of articles,wherein the surface features are more than 100 times smaller than themicrometer-sized pixel sensors.

In view of the foregoing, the single photon detector array or the numberof photon detector arrays may each include a complementary metal-oxidesemiconductor (“CMOS”) or a scientific complementary metal-oxidesemiconductor (“sCMOS”), each of which may optionally be part of CMOScamera or a sCMOS camera, respectively. Alternatively, the single photondetector array or the number of photon detector arrays may each includea charge-coupled device (“CCD”), which may optionally be part of CCDcamera. While a CCD-based photon detector array might have a slowerrecording speed than a CMOS-based or sCMOS-based photon detector array,a CCD-based photon detector array may be desirable in applicationsrequiring less electronic and/or image noise. A CCD-based photondetector array, including an electron-multiplying CCD (“EMCCD”), mayalso be desirable in certain applications having low-light conditions.Furthermore, a number of photon detector arrays is not limited tocombinations of either CMOS/sCMOS-based photon detector arrays orCCD-based photon-detector arrays, as a number of photon detector arraysmay include a combination of any of a number of CMOS/sCMOS-based photondetector arrays and CCD-based photon-detector arrays in applicationsthat benefit from employing each type of technology. In someembodiments, for example, a CMOS/sCMOS-based photon detector array maybe used to detect photons scattered from surface features of articles incertain applications having sufficient light for the CMOS/sCMOS-basedphoton detector array, while a CCD/EMCCD-based photon detector array maybe used to detect photons scattered from surface features of articles incertain applications having too little light for the CMOS/sCMOS-basedphoton detector array.

FIG. 3 provides a schematic for detection of surface features of anarticle, illustrating a close-up, cross-sectional view of an apparatusincluding an optical setup and a photon detector array. As shown,article 160 includes a surface 162 and one or more surface features suchas surface feature 164. Photons may be scattered by the surface featuresand collected and detected by a combination including a lens 120 coupledto a photon detector array 130, which combination may be positioned at adistance and/or an angle for an optimum acceptance of photons (e.g.,maximum acceptance of photons with minimum background noise) scatteredfrom one or more types of features. The optical setup, which may includea telecentric lens (e.g., lens 120 of FIG. 1A), may collect and focusthe photons scattered from one or more surface features onto one or morepixel sensors 132 of photon detector array 130, which one or more pixelsensors may each include a photon detector coupled to an amplifier(e.g., CMOS/sCMOS-based photon detector array; EMCCD-based photondetector array; etc.). The one or more pixel sensors 132, each of whichmay correspond to a particular, fixed area of an article's surface and apixel in a map of the article's surface, may provide one or more signalsto a computer or equivalent device for mapping an article's surface orotherwise determining the position of one or more features on thearticle's surface. FIG. 4 provides an image of such a surface featuresmap, FIG. 5 provides a close-up image of such a surface features map(e.g., a close-up image of the surface features map of FIG. 4), and FIG.6A further provides a close-up image of such a surface features map(e.g., a close-up image of the surface features map of FIG. 5), whereinthe close-up image of FIG. 6A is centered about a single surfacefeatures such as surface feature 164. The computer or equivalent devicemay subsequently use pixel interpolation for further mapping surfacefeatures such as surface feature 164 as provided in FIG. 6B.

Depending upon factors that may include the type of article, the type ofsurface features (e.g., particle, stain, scratch, void, etc.), and thelike, it may be desirable at times to increase detection time of asingle photon detector array or a number of photon detector arrays todetect more photons for detecting, mapping, and/or characterizingsurface features of articles. In some embodiments, for example,detection time of a single photon detector array or a number of photondetector arrays may be increased to detect more photons. In suchembodiments, a CCD-based photon detector array, including anelectron-multiplying EMCCD may be used to further detect more photons.Alternately, or in addition, it may be desirable to increase the numberof photons (e.g., photon energy) emitted from a single photon emitter ora number of photon emitters to provide an increase in photons scatteredfor detecting, mapping, and/or characterizing surface features ofarticles. Such an increase in photon energy may be with respect to unittime for increased photon power, or with respect to unit area forincreased photon flux density. Alternately to one or both of increasingthe photon energy or detection time, or in addition to increasing thephoton energy and detection time, it may be desirable at times tominimize background noise including stray light from one or more photonemitters, background light, and/or background fluorescent radiation.

The apparatus may further include one or more computers or equivalentdevices (e.g., devices that include primary and/or secondary memory andone or more processing elements operable to carry out arithmetic andlogical operations), including, but not limited to, servers,workstations, desktop computers, nettops, laptops, netbooks, and mobiledevices such as tablets and smartphones, which computers or equivalentdevices may contain graphics processing units (“GPU”s),application-specific integrated circuits (“ASIC”s), field-programmablegate arrays (“FPGA”s), etc. The computers or equivalent devices mayinclude a computer-readable storage medium for instructions making theapparatus operable to, but not limited to, convey each article to theapparatus for inspection; position each article for inspection,optionally including gradational or continuous rotation of the articlefor detecting, mapping, and/or characterizing surface features fromdifferent azimuthal angles; hold or otherwise maintain the position ofeach article for inspection; insert optical components into the opticalsetup, for example, using a mechanical actuator; position opticalcomponents for inspection; adjust optical components (e.g., focuslenses) and/or tune optical components (e.g., piezoelectric-basedwavelength filters; piezoelectric-based polarization filters; etc.) forinspection; remove optical components from the optical setup; move eachphoton emitter into position for inspection, wherein the position forinspection may include a photon emitter-article distance and/or angle(e.g., glancing angle) optimized for one or more types of features;switch each photon emitter on and off, or otherwise between modes foremitting photons and not emitting photons; move each photon detectorarray into position for inspection, wherein the position for inspectionmay include a photon detector array-article distance and/or angle (e.g.,scatter angle) optimized for one or more types of features; switch eachphoton detector array on and off, or otherwise between modes fordetecting photons and not detecting photons; synchronize each photonemitter with each photon detector in accordance with a photonemission-photon detection scheme; process photon detector array signalsfrom scattered photons, optionally including pixel interpolation forbetter accuracy (e.g., 10× better than pixel size) with respect to theposition of surface features; map or otherwise determine the position ofsurface features of articles from photon detector array signals orprocessed photon detector array signals (e.g., photon scatteringintensity distributions); quantitatively and/or qualitativelycharacterize surface features of articles; catalog surface features ofarticles; and determine trends with respect to surface features ofarticles.

The morphology, form, or shape of one or more surface features ofarticles, including one or more surface and/or subsurface defects, mayaffect the way in which the one or more surface features scatterphotons, an effect that may occur when photons are emitted onto asurface of an article from a single azimuthal angle. For example, asurface feature including an oxide may have a faceted surface thatscatters photons in a way that is not optimally detected or not detectedat all by a photon detector array when photons are emitted onto asurface of an article from a single azimuthal angle. In view of theforegoing, an apparatus in which photons are emitted onto a surface ofan article at a number of azimuthal angles may improve detection ofphotons scattered from surface features of articles by flushing outrotational dependencies, which, in turn, may result in optimal detectionof surface features and/or increased detection of surface features,thereby increasing the sensitivity of the apparatus and/or certaintythat as many of the surface features as possible are detected.

As provided herein, FIG. 1A provides a non-limiting schematic fordetecting, mapping, and/or characterizing surface features of articlesillustrating an apparatus 100. The apparatus 100 may include a photonemitter 110, an optical setup 120 including an optical component, aphoton detector array 130, a computer or equivalent device 140, anoptional stage 150 configured to support an article 160 and/or rotate anarticle 160 through a number of azimuthal angles, and a surface featuresmap 170 of a surface of the article 160, detailed description for thewhich is also provided herein. Turning to FIGS. 7A-7D, which draw uponFIG. 1A and the detailed description thereof, FIGS. 7A-7D providenon-limiting schematics illustrating detection of surface features ofarticles at a number of azimuthal angles. FIGS. 7A and 7B, for example,provide non-limiting schematics illustrating detection of surfacefeatures of articles at a number of azimuthal angles using a rotatablestage. FIGS. 7C and 7D, for example, provide non-limiting schematicsillustrating detection of surface features of articles at a number ofazimuthal angles using a number of photon emitters. While presentedseparately, the concepts presented herein with respect to FIGS. 7A and7B and the concepts presented herein with respect to FIGS. 7C and 7D maybe combined such that the detection of surface features of articles at anumber of azimuthal angles may be effected through both a rotatablestage and a number of photon emitters.

Turning to FIGS. 7A and 7B, FIG. 7A provides a non-limiting schematicillustrating detection of surface features of articles at a firstazimuthal angle using the stage 150, which stage 150 is configured torotate. As illustrated, the rotatable stage 150 may rotate the article160 such that it is azimuthally positioned at the first azimuthal anglefor a first surface features map 170A, or for collection of informationsufficient to produce the first surface features map 170A. The photonemitter 110 may emit photons onto the surface 162 of the article 160 atthe first azimuthal angle, scattering photons from surface features suchas surface feature 164A in the process. A photon detector array such asphoton detector array 130 of FIG. 1A may then detect photons scatteredfrom the surface features such as the surface feature 164A,photon-detector-array signals from which photon detector array may beused for the first surface features map 170A. FIG. 8A provides an imageof such a surface features map 170A at a nominal azimuthal angle of270°, in which the surface feature 164A is labeled “only 1 defect seen.”

FIG. 7B provides a non-limiting schematic illustrating detection ofsurface features of articles at a second azimuthal angle using therotatable stage 150. As illustrated, the rotatable stage 150 may rotatethe article 160 such that it is azimuthally positioned at the secondazimuthal angle for a second surface features map 170B, or forcollection of information sufficient to produce the second surfacefeatures map 170B. The photon emitter 110 may emit photons onto thesurface 162 of the article 160 at the second azimuthal angle, scatteringphotons from surface features in the process, such as scattering photonsfrom the surface feature 164A, as well as scattering photons from asurface feature 164B. The photon detector array may then detect photonsscattered from the surface features such as the surface feature 164A andthe surface feature 164B, which surface feature 164B may not have beenoptimally detected or not detected at all at the first azimuthal angle.As such, by virtue of rotating the article through the azimuthal angleα, surface features such as surface feature 164B are better detected oradditionally detected. As with first surface features map 170A,photon-detector-array signals from the photon detector array may be usedfor the second surface features map 170B. FIG. 8B provides an image ofsuch a surface features map 170B at a nominal azimuthal angle of 240°,in which the surface feature 164A and 164B are labeled “2 defects seen.”In view of the combination of surface features maps 170A and 170Bproviding better information or more information on surface features ofarticles than any one of surface features maps 170A and 170B, the numberof azimuthal angles at which photons are emitted on the surface of thearticle increases the sensitivity of the apparatus and/or the certaintythat as many of the surface features as possible are identified.

The rotatable stage 150 illustrated in FIGS. 7A and 7B may be configuredto gradationally rotate or continuously rotate the article 160respectively for piecewise or continuous detecting, mapping, and/orcharacterizing surface features. With respect to piecewise detecting,mapping, and/or characterizing surface features, the article 160 may besequentially rotated through a number of azimuthal angles, and thephoton emitter 110 may respectively sequentially (or continuously) emitphotons onto the surface of the article 160 at each successive azimuthalangle, scattering photons from the surface features of the article 160for sequential detection by the photon detector array (e.g., photondetector array 130). With respect to continuous detecting, mapping,and/or characterizing surface features, the article 160 may becontinuously rotated through a number of azimuthal angles, and thephoton emitter 110 may continuously emit photons onto the surface of thearticle 160, scattering photons from the surface features of the article160 for continuous (or as near continuous as desired or allowed, forexample, by technological limitations of the photon detector array)detection by the photon detector array (e.g., photon detector array130). Whether by sequential or continuous rotation through the number ofazimuthal angles, differential surface features maps such as 170A and170B, or the information sufficient to produce such surface featuresmaps 160A and 160B, may be used (e.g., contrasted) to qualitativelyand/or quantitatively characterize surface features and differentiatesuch surface features. In practice, any of a number of differentialsurface features maps (e.g., 160A, 160B, 160C . . . 160 n, wherein theindex n indicates the nth surface features map), or the informationsufficient to produce such surface features maps, may be used to effectthe foregoing. In addition, one or more composite surface features mapmay be generated from the differential surface features maps (or theinformation sufficient to produce such differential surface featuresmaps), providing one or more composite surface features maps fromselected azimuthal angles, including all possible azimuthal angles.

While the rotatable stage 150 of FIGS. 7A and 7B is illustrated torotate through an azimuthal angle of 90°, the rotatable stage 150 may beconfigured to rotate through a smaller azimuthal angle (e.g., 1°, 2°,3°, 5°, 10°, 25°, 45°, etc.) or larger azimuthal angle (e.g., 120°,180°, etc.) as deemed sufficient for detecting, mapping, and/orcharacterizing surface features of articles. Furthermore, while therotatable stage 150 is illustrated in FIGS. 7A and 7B to rotate througha single azimuthal angle, the rotatable stage 150 may be configured torotate through as many azimuthal angles as deemed sufficient fordetecting, mapping, and/or characterizing surface features of articles.Moreover, while the rotatable stage 150 is illustrated in FIGS. 7A and7B to rotate in an anti-clockwise direction, the rotatable stage 150 maybe alternatively configured to rotate in a clockwise direction or evenfurther alternatively configured to rotate in either an anti-clockwiseor a clockwise direction.

Turning to FIGS. 7C and 7D, FIG. 7C provides a non-limiting schematicillustrating detection of surface features of articles at a number ofazimuthal angles using a number of photon emitters 110A-110D. Asillustrated, a photon emitter 110A may be azimuthally positioned at afirst azimuthal angle to emit photons onto the surface 162 of thearticle 160 at the first azimuthal angle without rotation of the article160; however, in addition to supporting the article, the stage 150 maybe configured to rotate the article 160 in some embodiments. The photonemitter 110A may emit photons onto the surface 162 of the article 160from the first azimuthal angle, scattering photons from surface featuressuch as surface feature 164A in the process. A photon detector arraysuch as photon detector array 130 of FIG. 1A may then detect photonsscattered from the surface features such as the surface feature 164A fora first surface features map 170A, or for collection of informationsufficient to produce the first surface features map 170A. Signals fromthe photon detector array may subsequently be used for the first surfacefeatures map 170A. FIG. 8A provides an image of such a surface featuresmap 170A at a nominal azimuthal angle of 270°, in which the surfacefeature 164A is labeled “only 1 defect seen.”

FIG. 7D further provides a non-limiting schematic illustrating detectionof surface features of articles at a number of azimuthal angles using anumber of photon emitters 110A-110D. As illustrated, a photon emitter110B may be azimuthally positioned at a second azimuthal angle to emitphotons onto the surface 162 of the article 160 at the second azimuthalangle without rotation of the article 160. The photon emitter 110B mayemit photons onto the surface 162 of the article 160 from the secondazimuthal angle, scattering photons from surface features in theprocess, such as scattering photons from the surface feature 164A, aswell as scattering photons from a surface feature 164B. The photondetector array may then detect photons scattered from the surfacefeatures such as the surface feature 164A and the surface feature 164B,which surface feature 164B may not have been optimally detected or notdetected at all at the first azimuthal angle. As such, by virtue ofemitting photons onto the surface of the article through the azimuthalangle α, surface features such as surface feature 164B are betterdetected or additionally detected. As with first surface features map170A, photon-detector-array signals from the photon detector array maybe used for the second surface features map 170B. FIG. 8B provides animage of such a surface features map 170B at a nominal azimuthal angleof 240°, in which the surface features 164A and 164B are labeled “2defects seen.” In view of the combination of surface features maps 170Aand 170B providing better information or more information on surfacefeatures of articles than any one of surface features maps 170A and170B, the number of azimuthal angles at which photons are emitted on thesurface of the article increases the sensitivity of the apparatus and/orthe certainty that as many of the surface features as possible areidentified.

The photon emitters 110A-D illustrated in FIGS. 7C and 7D may beconfigured to sequentially or simultaneously emit photons onto thesurface 162 of the article 160 respectively for piecewise orsimultaneous detecting, mapping, and/or characterizing surface features.With respect to piecewise detecting, mapping, and/or characterizingsurface features, photons be sequentially emitted onto the surface ofthe article 160 through a number of azimuthal angles, for example, byphoton emitter 110A, followed by photon emitter 110B, followed by photonemitter 110C, and so on, scattering photons from the surface features ofthe article 160 for sequential detection by the photon detector array(e.g., photon detector array 130). With respect to continuous detecting,mapping, and/or characterizing surface features, photons besimultaneously emitted onto the surface of the article 160 through anumber of azimuthal angles, for example, by each of photon emitters110A-D at the same time, scattering photons from the surface features ofthe article 160 for detection by the photon detector array (e.g., photondetector array 130). Whether by emitting photons sequentially orsimultaneously through the number of azimuthal angles, differentialsurface features maps such as 170A and 170B, or the informationsufficient to produce such surface features maps 160A and 160B, may beused (e.g., contrasted) to qualitatively and/or quantitativelycharacterize surface features and differentiate such surface features.In practice, any of a number of differential surface features maps(e.g., 160A, 160B, 160C . . . 160 n, wherein the index n indicates thenth surface features map), or the information sufficient to produce suchsurface features maps, may be used to effect the foregoing. In addition,one or more composite surface features map may be generated from thedifferential surface features maps (or the information sufficient toproduce such differential surface features maps), providing one or morecomposite surface features maps from selected azimuthal angles,including all possible azimuthal angles.

While the number of photon emitters 110A-D of FIGS. 7C and 7D areillustrated to be positioned an azimuthal angle of 90° apart from eachother, the number of photon emitters, which are not limited in number,may be positioned a smaller azimuthal angle (e.g., 1°, 2°, 3°, 5°, 10°,25°, 45°, etc.) apart from each other or a larger azimuthal angle (e.g.,120°, 180°, etc.) apart from each other as deemed sufficient fordetecting, mapping, and/or characterizing surface features of articles.Furthermore, while FIGS. 7C and 7D illustrate four photon emitters, theapparatus may include any of a number of photon emitters sufficient toeffect the number of azimuthal angles for detecting, mapping, and/orcharacterizing surface features of articles, examples of the number ofphoton emitters being provided herein, including the photon emitters110A-D of FIGS. 7C and 7D. Moreover, while the photon emitters 110A-D ofFIGS. 7C and 7D are illustrated to emit photons in an anti-clockwisedirection, the number of photon emitters may be alternatively configuredto emit photons in a clockwise direction or even further alternativelyconfigured to emit photons in either an anti-clockwise or a clockwisedirection.

The apparatus may be configured for detecting, mapping, and/orcharacterizing surface features of articles, wherein the surfacefeatures are nanometer-sized (i.e., admits of nm units as measured) orsmaller in their smallest dimension (e.g., length, width, height, ordepth, depending on the surface feature), which surface features may besmaller than the wavelength of photons emitted from a photon emitter ofthe apparatus. However, the apparatus is not limited to surface featuresof articles that are nanometer-sized or smaller, as the apparatus may beconfigured for detecting, mapping, and/or characterizing surfacefeatures of articles, wherein the surface features are micrometer-sized(i.e., admits of μm units as measured) or larger. In some embodiments,for example, the apparatus may be configured for detecting, mapping,and/or characterizing surface features of articles, wherein the surfacefeatures are smaller than 500 nm, 250 nm, 200 nm, 150 nm, 125 nm, 110nm, 100 nm, 90 nm, 80 nm, 70 nm, 60 nm, 50 nm, 40 nm, 30 nm, 20 nm, 10nm, or 1 nm (10 Å) in their smallest dimension, or even smaller, such assurface features of articles smaller than 9 Å, 8 Å, 7 Å, 6 Å, 5 Å, 4 Å,3 Å, 2 Å, or 1 Å in their smallest dimension. In view of the foregoing,and in some embodiments, for example, the apparatus may be configuredfor detecting, mapping, and/or characterizing surface features ofarticles, wherein the surface features are between 0.1 nm and 1000 nm,such as between 0.1 nm and 500 nm, including between 0.1 nm and 250 nm,and further including between 0.1 nm and 100 nm, and even furtherincluding between 0.1 nm and 80 nm. Furthermore, the apparatus may beconfigured for detecting, mapping, and/or characterizing subsurfacefeatures, such as subsurface defects, wherein the subsurface featureshave a depth more than 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9nm, or 10 nm, or deeper.

The apparatus may be configured for detecting, mapping, and/orcharacterizing surface features of articles, including surface and/orsubsurface defects including particle contamination in which theparticles are nanometer-sized (i.e., admits of nm units as measured) orsmaller in their smallest dimension (e.g., length, width, or height). Insome embodiments, for example, the apparatus may be configured fordetecting, mapping, and/or characterizing surface and/or subsurfaceparticles smaller than 125 nm, such as smaller than 100 nm, includingsmaller than 80 nm, and further including smaller than 10 nm in theirsmallest dimension. Detecting, mapping, and/or characterizing surfaceand/or subsurface particles down to the level of 10 nm in height isimportant for hard disks of hard disk drives, as particles greater than10 nm in height (e.g., from the surface) may corrupt the spacing betweenthe hard disk and the read-write head of a hard disk drive. In someembodiments, for example, the apparatus may be configured for detecting,mapping, and/or characterizing surface and/or subsurface particles assmall as or smaller than 4 nm in height.

The apparatus may be configured for detecting, mapping, and/orcharacterizing surface features of articles, including surface and/orsubsurface defects including scratches (e.g., circumferential scratches)that are micrometer-sized (i.e., admits of μm units as measured) orsmaller, such as nanometer-sized (i.e., admits of nm units as measured)or smaller, such as angstrom-sized (i.e., admits of Å units as measured)or smaller, in their smallest dimension (e.g., length, width, or depth).With respect to micrometer-sized scratches, the apparatus may beconfigured for detecting, mapping, and/or characterizing scratches from,for example, 1 μm to 1000 μm in length, which may be significantlylonger than the wavelength of photons emitted from a photon emitter ofthe apparatus. In some embodiments, for example, the apparatus may beconfigured for detecting, mapping, and/or characterizing scratchessmaller than 1000 μm, such as smaller than 500 μm, including smallerthan 250 μm, further including smaller than 100 μm, and even furtherincluding smaller than 50 μm in scratch length. With respect tonanometer-sized scratches, the apparatus may be configured fordetecting, mapping, and/or characterizing scratches from, for example, 1nm to 500 nm in scratch width. In some embodiments, for example, theapparatus may be configured for detecting, mapping, and/orcharacterizing scratches smaller than 500 nm, such as smaller than 250nm, including smaller than 100 nm, further including smaller than 50 nm,and even further including smaller than 15 nm in scratch width.Surprisingly, due to a high level of spatial coherence, the apparatusmay be configured for detecting, mapping, and/or characterizingangstrom-sized scratches with respect to scratch depth. In someembodiments, for example, the apparatus may be configured for detecting,mapping, and/or characterizing scratches smaller than 50 Å, such assmaller than 25 Å, including smaller than 10 Å, further includingsmaller than 5 Å, and even further including smaller than 1 Å (e.g., 0.5Å) in scratch depth. For example, the apparatus may be configured fordetecting, mapping, and/or characterizing scratches smaller than 500 μmin length, smaller than 100 nm in width, and smaller than 50 Å in depth.

The apparatus may be operable to accurately and/or precisely map orotherwise determine the position of a surface feature (e.g., FIGS. 6A[top] and 6B [top]) on an article's surface. With respect to accuracy,the apparatus may be operable to map or otherwise determine the positionof a feature on an article's surface within a micrometer-sized (i.e.,admits of μm units as measured) radius or better. In some embodiments,for example, the apparatus may be operable to accurately map orotherwise determine the position of a feature on an article's surfacewithin a radius of 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30μm, 20 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1μm, or better. Combinations of the foregoing may also be used todescribe the accuracy with which the apparatus may map or otherwisedetermine the position of a feature on an article's surface. In someembodiments, for example, the apparatus may be operable to accuratelymap or otherwise determine the position of a feature on an article'ssurface within a radius ranging from 1 μm to 100 μm, such as from 1 μmto 50 μm, including from 1 μm to 30 μm, and further including from 5 μmto 10 μm.

In addition to accurately and/or precisely mapping or otherwisedetermining the position of a feature on a surface of an article, theapparatus may be operable to accurately and/or precisely determine thephoton scattering intensity distribution (e.g., FIGS. 6A [bottom] and 6B[bottom]) of the feature on the surface of the article. Such a photonscattering intensity distribution may be used characterize a surfacefeature of an article both quantitatively and qualitatively.

With respect to quantitative characterization of a surface feature of anarticle, mathematical integration of a photon scattering intensitydistribution provides the size (e.g., volume) of the surface feature ofthe article. Quantitative characterization of a surface feature of anarticle may further include a determination of surface feature positionon the article as described herein. Quantitative characterization mayeven further include the total number of surface features per article,or the number of surface features per unit area per article, as well asthe number of each type of surface feature on the article. Suchcharacterization information may be cataloged across a number ofarticles and be used to correct manufacturing trends should suchfeatures include surface and/or subsurface defects that might degradethe performance of the article.

With respect to qualitative characterization of a surface feature of anarticle, qualitative characterization may include a determination of themorphology, form, or shape of the surface feature of the article,including whether the surface feature is a particle, a stain, a scratch,or a void, etc., which determination may be effected by, but is notlimited to, analysis of photon scattering intensity distributions.Qualitative characterization may further include chemicalcharacterization of surface features known to differentially scatterphotons such as, but not limited to, certain oxides, which may havefaceted surfaces that differentially and/or directionally scatterphotons. Qualitative characterization may even further includedistinguishing between surface features known to differentially scatterphotons with respect to wavelength; a polarization filter may be used todistinguish between surface features known to differentially scatterphotons with respect to polarization; a coherence filter may be used todistinguish between surface features known to differentially scatterphotons with respect to coherence; and a phase filter or waveplate maybe used to distinguish between surface features known to differentiallyscatter photons with respect to phase. In some embodiments, for example,qualitative characterization of one or more surface features of anarticle may include contrasting photon-scattering information in theeffective absence of one of the foregoing filters with photon-scatteringinformation using one or more of the foregoing filters or contrasting afirst surface features map produced in the effective absence of one ofthe foregoing filters with a second surface features map (or a number ofsurface features maps) produced using one or more of the foregoingfilters. Along with quantitative characterization information, suchqualitative characterization information may be cataloged across anumber of articles and be used to correct manufacturing trends shouldsuch features include surface and/or subsurface defects that mightdegrade the performance of the article.

The apparatus described herein may be configured to process or inspectarticles at a rate greater than or commensurate with the rate at whichthe articles or workpieces thereof are produced. In some embodiments,for example, the apparatus may be configured to process or inspectarticles at a rate of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14,16, 18, or 20, or higher, article(s) per second, which rate may becommensurate with the rate at which the articles or workpieces thereofare produced. In some embodiments, for example, the apparatus may beconfigured to process or inspect articles at a rate of no more than 20,18, 16, 14, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 article(s) per second,which rate may be commensurate with the rate at which the articles orworkpieces thereof are produced. Combinations of the foregoing may alsobe used to describe the rate at which the articles or workpieces thereofare processed or inspected by the apparatus. In some embodiments, forexample, the apparatus may be configured to process or inspect at least1 and no more than 20 articles per second (e.g., between 1 and 20articles per second), such as at least 1 and no more than 10 articlesper second (e.g., between 1 and 10 articles per second), including atleast 1 and no more than 5 articles per second (e.g., between 1 and 5articles per second). Processing or inspecting articles at rates greaterthan or commensurate with the rate at which the articles or workpiecesthereof are produced is a function of many features of the apparatusdescribed herein, including, but not limited to, photon emitters and/orarticles that need not be moved (e.g., for scanning) during processingor inspecting. For example, with a number of photon emitters such asphoton emitters 110A-D of FIGS. 7C and 7D, an article such as a harddisk of a hard disk drive need not be rotated during processing orinspecting. As such, the apparatus may be configured to hold an articlestationary while emitting photons onto the surface of the article.

As such, provided herein is an apparatus, comprising a photon emittingmeans configured to emit photons onto a surface of an article at aplurality of azimuthal angles; a photon detector array configured toreceive photons scattered from surface features of the article; and aprocessing means configured to 1) process photon-detector-array signalscorresponding to the photons scattered from the surface features of thearticle and 2) morphologically characterize the surface features of thearticle. In some embodiments, the apparatus further comprises atelecentric lens coupled to the photon detector array. In someembodiments, the processing means is further configured to generate atleast one surface features map for the article from thephoton-detector-array signals corresponding to the photons scatteredfrom the surface features of the article. In some embodiments, theprocessing means is further configured to generate a plurality ofsurface features maps for the article from the photon-detector-arraysignals corresponding to the photons scattered from the surface featuresof the article, wherein the plurality of surface features mapsrespectively correspond to the plurality of azimuthal angles. In someembodiments, the processing means comprises one or more computers orequivalent devices configured to process the photon-detector-arraysignals corresponding to the photons scattered from the surface featuresof the article. In some embodiments, the photon emitting means comprisesat least one photon emitter and a stage configured to support thearticle. In some embodiments, the stage is further configured forrotating and azimuthally positioning the article with respect to the atleast one photon emitter, wherein azimuthally positioning the articlewith respect to the at least one photon emitter allows for emittingphotons onto the surface of the article at the plurality of azimuthalangles. In some embodiments, a plurality of photon emitters arerespectively positioned around the stage at the plurality of azimuthalangles for emitting photons onto the surface of the article at theplurality of azimuthal angles.

Also provided herein is an apparatus, comprising a photon emitting meansconfigured to emit photons onto a surface of an article at a pluralityof azimuthal angles; and a processing means configured to 1) processphoton-detector-array signals corresponding to photons scattered fromsurface features of the article and 2) generate one or more surfacefeatures maps for the article from the photon-detector-array signalscorresponding to the photons scattered from the surface features of thearticle. In some embodiments, the apparatus further comprises atelecentric lens coupled to a photon detector array. In someembodiments, the one or more surface features maps comprises a pluralityof surface features maps respectively corresponding to the plurality ofazimuthal angles. In some embodiments, the one or more surface featuresmaps comprises a composite surface features map of a plurality ofsurface features maps respectively corresponding to the plurality ofazimuthal angles. In some embodiments, the processing means comprisesone or more computers or equivalent devices configured to process thephoton-detector-array signals corresponding to the photons scatteredfrom the surface features of the article. In some embodiments, thephoton emitting means comprises at least one photon emitter and arotatable stage configured for supporting and azimuthally positioningthe article with respect to the at least one photon emitter, whereinazimuthally positioning the article with respect to the at least onephoton emitter allows for emitting the photons onto the surface of thearticle at the plurality of azimuthal angles.

Also provided herein is an apparatus, comprising a photon detector arraycomprising a plurality of photon detectors configured to receive photonsscattered from surface features of an article; and a processorconfigured to 1) process photon-detector-array signals corresponding tothe photons scattered from the surface features of the article and 2)generate a plurality of surface features maps for the article from thephoton-detector-array signals corresponding to the photons scatteredfrom the surface features of the article, wherein the plurality ofsurface features maps respectively correspond to a plurality ofazimuthal angles at which photons are emitted onto a surface of thearticle. In some embodiments, the apparatus further comprises atelecentric lens coupled to the photon detector array. In someembodiments, the processor is further configured to generate a compositesurface features map for the article from the plurality of surfacefeatures maps for the article. In some embodiments, the processor is ofone or more computers or equivalent devices configured to process thephoton-detector-array signals corresponding to the photons scatteredfrom the surface features of the article. In some embodiments, theapparatus further comprises a photon emitting means for emitting photonsonto the surface of the article at the plurality of azimuthal angles. Insome embodiments, the photon emitting means comprises at least onephoton emitter and a rotatable stage configured for supporting andazimuthally positioning the article with respect to the at least onephoton emitter, wherein azimuthally positioning the article with respectto the at least one photon emitter allows for emitting the photons ontothe surface of the article at the plurality of azimuthal angles.

While some particular embodiments have been described and/or illustratedherein, and while these particular embodiments have been describedand/or illustrated in considerable detail, it is not the intention ofthe applicant(s) for these particular embodiments to limit the scope ofthe concepts presented herein. Additional adaptations and/ormodifications may readily appear to persons having ordinary skill in theart, and, in broader aspects, these adaptations and/or modifications maybe encompassed as well. Accordingly, departures may be made from theforegoing embodiments without departing from the scope of the conceptsprovided herein. The implementations provided herein and otherimplementations are within the scope of the following claims

What is claimed is:
 1. An apparatus comprising: a photon emitterconfigured to emit photons onto a surface of an article at an azimuthalangle and with an emitting wavelength, wherein the photon emitter ispositioned at an emitting distance from the surface of the article; aphoton detector array configured to receive photons scattered fromsurface features of the article at a reflective azimuthal angle with areflecting wavelength, wherein the photon detector array is positionedat a receiving distance from the surface of the article; and aprocessing unit configured to process a plurality ofphoton-detector-array signals corresponding to the photons scatteredfrom the surface features of the article and morphologicallycharacterize the surface features of the article based on the azimuthalangle, the emitting wavelength, the reflective azimuthal angle, thereflecting wavelength, the emitting distance, and the receiving distanceto distinguish between different surface feature types.
 2. The apparatusof claim 1, wherein the different surface features types includes aparticle, stain, scratch, and void surface features.
 3. The apparatus ofclaim 1, wherein the morphologically characterizing the surface featuresis further based on polarization, coherency, and phase associated withthe emitting photons and the received photons.
 4. The apparatus of claim1, wherein the photon emitter comprises a light emitting diode (LED)based ring configured to enhance circumferential scratches and voids onthe surface of the article by emitting photons at a glancing angle ofless than 45°.
 5. The apparatus of claim 1, wherein the photon emitteris further configured to emit photons onto the surface of the article ata different azimuthal angle subsequent to emitting photons at theazimuthal angle through gradational rotation of the article, and whereinthe photon detector array is further configured to receive photonsscattered from the surface features of the article at a differentreflective azimuthal angle.
 6. The apparatus of claim 1, wherein theprocessing unit is configured to determine a size associated with eachsurface feature of the surface features by processing photon scatteringintensity distribution associated with the received photons scatteredfrom the surface features of the article.
 7. The apparatus of claim 1,wherein the processing unit is further configured to distinguish betweenthe different surface feature types through differential analysis ofwavelength and polarization for received photons scattered from thesurface features of the article.
 8. The apparatus of claim 1, whereinthe processing unit is further configured to distinguish between thesurface feature types through differential analysis of phase andcoherency of photons scattered from the surface features of the article.9. The apparatus of claim 1 further comprising: a first componentselected from a group consisting of a wavelength filter, a bandpassfilter, a polarization filter, a coherence filter, a periodic arraytuned filter, and a phase filter, wherein the component is coupled tothe photon emitter to alter characteristics of the photons emitted; anda second component selected from a group consisting of a wavelengthfilter, a bandpass filter, a polarization filter, a coherence filter, aperiodic array tuned filter, and a phase filter, wherein the componentis coupled to the photon detector array to alter characteristics of thereceived photons scattered from the surface features of the article. 10.An apparatus comprising: a first photon emitter configured to emitphotons onto a surface of an article at a first azimuthal angle, with afirst emitting wavelength, a first polarization, a first coherency, anda first phase, wherein the first photon emitter is positioned at a firstdistance from the surface of the article; a second photon emitterconfigured to emit photons onto a surface of an article at a secondazimuthal angle, with a second emitting wavelength, a secondpolarization, a second coherency, and a second phase, wherein the secondphoton emitter is positioned at a second distance from the surface ofthe article, and wherein the first distance, the first azimuthal angle,the first emitting wavelength, the first polarization, the firstcoherency and the first phase are different from the second distance,the second azimuthal angle, the second emitting wavelength, the secondpolarization, the second coherency and the second phase respectively todistinguish between feature types on the surface of the article; aphoton detector array configured to receive photons scattered fromsurface features of the article at a plurality of reflective azimuthalangles, a plurality of reflective wavelengths, a plurality of reflectivepolarizations, a plurality of reflective coherencies, and a plurality ofreflective phases, wherein the photon detector array is positioned at areceiving distance from the surface of the article; and a processingunit configured to process a plurality of photon-detector-array signalscorresponding to the photons scattered from the surface features of thearticle and morphologically characterize the surface features of thearticle based on the distance, azimuthal angle, wavelength,polarization, coherency, and phase associated with photons of the firstphoton emitter, the second photon emitter, and the photon detector arrayto distinguish between different surface feature types.
 11. Theapparatus of claim 10, wherein the different surface features typesincludes a particle, stain, scratch, and void surface features.
 12. Theapparatus of claim 10, wherein the first photon emitter comprises alight emitting diode (LED) based ring configured to enhancecircumferential scratches and voids on the surface of the article byemitting photons at a glancing angle of less than 45°.
 13. The apparatusof claim 10, wherein the processing unit is configured to determine asize associated with each surface feature of the surface features byprocessing photon scattering intensity distribution associated with thereceived photons scattered from the surface features of the article. 14.The apparatus of claim 10, wherein the processing unit is furtherconfigured to distinguish between the different surface feature typesthrough differential analysis of wavelength and polarization forreceived photons scattered from the surface features of the article. 15.The apparatus of claim 10, wherein the processing unit is furtherconfigured to distinguish between the surface feature types throughdifferential analysis of phase and coherency of photons scattered fromthe surface features of the article.
 16. The apparatus of claim 10further comprising: a first component coupled to the first photonemitter, wherein the first component comprises a wavelength filter, apolarization filter, a coherence filter, and a phase filter to emitphotons at the first wavelength, the first polarization, the firstcoherency, and the first phase; a second component coupled to the secondphoton emitter, wherein the second component comprises a wavelengthfilter, a polarization filter, a coherence filter, and a phase filter toemit photons at the second wavelength, the second polarization, thesecond coherency, and the second phase; and a third component coupled tothe photon detector array, wherein the third component comprises aplurality of wavelength filters, a plurality of polarization filters, aplurality of coherence filters, and a plurality of phase filters todetect scattered photons at the plurality of reflective wavelengths, theplurality of reflective polarizations, the plurality of reflectivecoherencies, and the plurality of reflective phases.
 17. An apparatuscomprising: a photon emitter, at a first instance in time, configured toemit photons onto a surface of an article at a first azimuthal angle,with a first emitting wavelength, a first polarization, a firstcoherency, and a first phase, wherein the first photon emitter ispositioned at a first distance from the surface of the article at thefirst instance in time, and wherein the photon emitter at a secondinstance in time subsequent to the first instance in time is configuredto emit photons onto the surface of the article at a second azimuthalangle, with a second emitting wavelength, a second polarization, asecond coherency, and a second phase, wherein the photon emitter ispositioned at a second distance from the surface of the article at asecond instance in time; a photon detector array configured to receivephotons scattered from surface features of the article at a plurality ofreflective azimuthal angles, a plurality of reflective wavelengths, aplurality of reflective polarizations, a plurality of reflectivecoherencies, and a plurality of reflective phases, wherein the photondetector array is positioned at a receiving distance from the surface ofthe article; and a processing unit configured to process a plurality ofphoton-detector-array signals corresponding to the photons scatteredfrom the surface features of the article and morphologicallycharacterize the surface features of the article based on the distances,azimuthal angles, wavelengths, polarizations, coherencies, and phasesassociated with photons of the photon emitter, and the photon detectorarray to distinguish between different surface feature types.
 18. Theapparatus of claim 17, wherein the photon emitter comprises a lightemitting diode (LED) based ring configured to enhance circumferentialscratches and voids on the surface of the article by emitting photons ata glancing angle of less than 45°.
 19. The apparatus of claim 17,wherein the processing unit is configured to determine a size associatedwith each surface feature of the surface features by processing photonscattering intensity distribution associated with the received photonsscattered from the surface features of the article.
 20. The apparatus ofclaim 17, wherein the processing unit is further configured to identifychemical characterization of oxides of the surface features.